Question

If tan2A=cot(A+60)find the valu of A where 2A is acute angle

Answer 1

Hi
Tan2A=tan(90-(A+60))
Means
2A=30-A
A=10
2A=20(<90)

Answer 2

 Solution:

It is given that tan2A=cot(A−18°)

 ⇒tan2A=cot(90° −(108° −A))

⇒tan2A=tan(108° −A)        

{°•° cot(90° −A)=tan(A)}

 ⇒2A=108° −A

 ⇒3A=108°

 ⇒A=108°/3 =36°

Thanks ☺